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Steenkamp:
Hi All, Im Rhynardt from Swaziland. Been a lurker on Mad Modder for a bit now just sucking in info. I have a small machine shop with a Myford ML7 lathe, a unknown beleived to be Russian round bed lathe and a TomSenior M1 mill. Have dabbled around with small steam and sterling engines, turbines and tooling. Current work in progress builds are a tool and cutter grinder made from a old Black & Decker valve grinder , another gravograph single lip cuttergrinder i have modded to gring the ends of milling cutters and giving the round bed russian a powerfeed.

My Tom Senior has a "Knuckle Head" vertical attachment and i use this for most milling tasks. My problem with it though is that the head severely limits headspace and the worst problem is my two helical drivegears for the spindle in the head are almost non existant. I think the machine had a very productive previous live as they are worn very sharp! Getting new gears made will cost more than i would pay for a chinese mill! I really dont want to part with the Senior as its a superb, very rigid and still accurate machine.
What i have been contemplating is to build a new "M head" type spindle that bolts to the top of the machine and remove the knuckle head completely. What bearings could i cost effectively use. I did some enquiries regarding "super precision" angular contact bearings and the pricing on those are prohibitive. Any other suggestions?

PekkaNF:
Wellcome! Here seems to be some people from RSA.

RE: Shopbuild spindle and bearings...I have been tinkering with some stuff like that and I have arrived to this:

1) Book Spindles by Harprit Sandhu
http://bbs.homeshopmachinist.net/threads/1360-Book-Review-Spindles-by-Harprit-Sandhu
This might a little basic, but still best I have found for amateur. Some "metric" dimensions and bearing sizes are funny, best to check.

2) Super accuracy bearings are more of a nuisance than benefit on homebuild....If you read the bearing book, your head will spin when you see requirements even for a normal bearing housing dimensional accuracy. More stiffer and accurate bearings you require harder it gets and let's not forget the preload, lubrication and heat buildup. Yherefore I recommend using C3 for ball bearings and standard for angular contact bearings and taper roller bearings.

http://www.skf.com/ph/products/bearings-units-housings/roller-bearings/principles/bearing-data-general/bearing-internal-clearance/index.html

3) Main Loading direction and rpm will get you very close to correct bearing:
* Slow rpm and lots of load = taper roller bearing. Cheap (wheel bearings and such), but you need external shield/seals.
* High rpm and you don't plan hitting the arbor to free the MT-taper = angular contact bearings. These are pretty cheap and often come with a seal.

Then only thing left is to use them in opposing pairs or use another arrangement  for preload and temperature compensation. That's pretty much all I know there are people on this board who know these things or have build something similar. Why not make a thread on this one, lot's of pictures of the "victim" and some doodle?


pekka

Steenkamp:
Hi Pekka, thanks for the advise. I was thinking around the same thing regarding standard angular contact bearings, just didnt wanna say it out load incase i offend the purists. Will definately post some pics of my machines. Watch this space a bit later today.

vtsteam:
Hi Rhynardt, welcome!!! :beer: Looking forward to your progress, photos, and contributions!

Don't worry about "offending purists" here. Not enough purists to offend on MadModders! Opinions, yes, but usually when asked for. Generally an extremely helpful, interested, and supportive group.

I'm not familiar with your mill attachement, so if it has a quill, this wouldn't apply, but if not, it's possible to buy a spindle and tapered roller bearings meant for a mini-lathe quite reasonably, and it's ground, keyed, pre-bored for and MT taper.

Personally, though (here comes the opinion) I'd be very interested, if it were mine, in cutting new helical gears for the spindle. Where there's a will there's a way, and I bet with some research, it coud be done in the home shop.

There was a great gear cutter project by DT Jacobs in old ME's that certainly could have done it, and I think a simpler shop built fixture for a one-off job might be built for the lathe (or mill) with some thought about the requirements.

Anyway, once again, welcome aborad!  :beer:

krv3000:
hi and welcome

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